Bosch 250SX NG, 250SX LP User Manual

MODEL 250SX NG and 250SX LP

Temperature Modulated with Electronic Ignition

Suitable for heating potable water only

Not approved for space heating purposes

(Intended for variable flow applications with multiple tapping points)

250 SX NG 250 SX LP

Warning: If the information in this manual is not

followed exactly, a fire or explosion may result causing property damage, personal injury or death. Do not store or use gasoline or other flammable vapor and liquids in the vicinity of this or any other appliance.

Improper installation, adjustment, alteration, service or maintenance can cause injury or property damage. Refer to this manual. For assistance or additional information consult a qualified installer, service agency or the gas supplier. In the Commonwealth of Massachusetts this product must be installed by a licensed plumber or gas fitter.

Upon completion of the installation, these instructions should be handed to the user of the appliance for future reference.

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What to do if you smell gas

• Close gas valve. Open windows.

• Do not try to light any appliance.

• Do not touch any electrical switch; do not use any phone in your building.

• If you cannot reach your gas supplier, call the fire department.

• Immediately call your gas supplier from a neighbor’s phone. Follow the gas supplier’s instructions

• Installation and service must be performed by a qualified installer, service agency or the gas supplier.

Index

1Warning 2

2 Appliance details 4

2.1 Features 4

2.2 250 SX Specifications (Technical data) 4

2.3 Dimensions and Minimum installation clearances 6

2.4 General rules to follow for safe operation 7

2.5 Proper location for installing your heater 7

2.6 Clearances 8

2.7 Mounting installation 8

2.8 Combustion air requirements 8

2.9 Venting 9

2.9.1 Venting options 11

2.10 Gas piping & connections 15

2.11 Gas line sizing 17

2.12 Measuring gas pressure 17

2.13 Water connections 18

2.14 Electrical connections 19

2.15 Operating instructions 19

2.16 For your safety read before operating your water heater 19

2.17 Lighting and operating instructions 19

3 Operation instructions 21

3.1 Power 21

3.2 Temperature selection 21

3.3 Use of remote control accessory 23

3.4 Operation 23

3.5 Reset button 23

3.6 Program button 23

3.7 Locked condition 23

1Warning

Warning: If the information in this

manual is not followed exactly. A fire or explosion may result causing property damage, personal injury or death.

Warning: Improper installation, adjustment, alteration, service or maintenance can cause injury or property damage. Refer to this manual. For assistance or additional information consult a qualified installer, service agency or the gas supplier. Upon completion of the installation, these instructions should be handed to the user of the appliance for future reference.

Featuring

Electronic Ignition and Power Venting

For your safety

Do not store or use gasoline or other flammable, combustible or corrosive vapors and liquids in the vicinity of this or any other appliance.

4 Maintenance and service 24

5 Troubleshooting 24

6 Electrical diagram 27

7 250 SX Functional scheme 28

8 Interior components diagram and parts list 29

8.1 Interior components 29

8.2 Components diagram 30

8.3 Parts list 31

9 Special adjustment for measuring and adjusting CO2

levels 32

9.1 Adjusting the unit 32

9.1.1 CO2 measuring port 32

9.1.2 Selecting adjustment mode 32

10 Protecting the environment 34

11 Twelve Year Limited Warranty 35

Warning: Carefully plan where you

install the heater. Correct combustion air supply and flue pipe installation are very important. If a gas appliance is not installed correctly, fatal accidents can result from lack of air, carbon monoxide poisoning or fire.

Warning: Exhaust gas must be vented to outside using proper vent material suitable for category III vent systems and temperatures up to 480°F. Vent and combustion air connector piping must be sealed gas-tight to prevent possibility of flue gas spillage, carbon monoxide emissions and risk of fire, resulting in severe personal injury or death.

Warning: Place the heater in a location where water leaks will do NO DAMAGE to adjacent areas or lower floors.

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Warning: Field wiring connections and electrical grounding must comply with local codes, or in the absence of local codes, with the latest edition of the National Electric Code, ANSI/NFPA 70, or in Canada, all electrical wiring must comply with the local codes and the Canadian Electrical Code, CSA C22.1 Part 1.

Warning: Shock hazard line voltage is present. Before servicing the water heater, turn off the electrical power to the water heater at the main disconnect or circuit breaker. Failure to do so could result in severe personal injury or death.

What to do if you smell gas

• Close gas valve. Open windows.

• Do not try to light any appliance.

• Do not touch any electrical switch; do not use any phone in your building.

• Immediately call your gas supplier from a neighbor’s phone. Follow the gas supplier’s instructions.

• If you cannot reach your gas supplier, call the fire department.

• Installation and service must be performed by a qualified installer, service agency or the gas supplier.

Warning

Fig. 1

Warning: The heater must be disconnected from the gas supply piping system during any pressure testing of that system at test pressures equal to or more than 0.5 psig.

FCC: This device complies with Part 15 of the FCC rules. Operation is subject to the following two conditions: (1) This device may not cause harmful interference, and (2) this device must accept any interference received, including interference that may cause undesired operation.

Caution: Any changes or modifications not expressly approved by the party responsible for compliance could void the user’s authority to operate the equipment.

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Fig. 2

Appliance details

2 Appliance details

2.1 Features

Parts

• Touch Pad interface control

• High power pre-mix compact burner with low Nox emissions

• Modulating Gas Valve with constant gas:air ratio control

• Modulating water valve for improved comfort and temperature control.

Safety

• Flame sensor (ionization) rod

• Overheat sensor

• Temperature limiter

• Fan speed monitoring.

High Quality Materials for Long Working Life

• Copper heat exchanger

• Ceramic Burner output

• Automatic overheating protection shut-off sensor

• Compact space saver: mounts on a wall with a supplied bracket.

• Easily removable one-piece cover.

Features

• LCD Display

• On/Off and Temperature control switches

• Reset button

• Program Key (Selectable temperature default)

• Failure codes for easy diagnostic and repair.

Accessories

• Optional wireless remote control accessory to operate with the appliance

Maximum input

175,000 Btu/h (51.2 kW)

Efficiency in %

Recovery efficiency 86.5%

Min. Output

31,131 Btu/h (9.1 kW)

Temperature Control

Selection range: 100°F (38°C) - 140°F (60°C) Default temperature: 122°F (50°C) Stability: +/- 2°F (+/- 1°C)

Gas Requirement

Gas connection (inches) - ¾” Inlet gas pressure under operation (with a high hot

water flow rate)*

• Propane: 11” - 14” water column

• Natural Gas: 5” - 14” water column

• Gas pressure measuring point inside the appliance at the gas valve inlet.

* Testing with a manometer, operate other gas equipment on the same gas supply. Gas pressures lower than 5" W.C. for Natural Gas or 11" W.C. for LPG will result in insufficient degree rise to the hot water being used. See Measuring Gas Pressure, chapter 2.12.

• Vent termination kit.

BOSCH is constantly improving its products, therefore specifications are

subject to change without prior notice.

2.2 250 SX Specifications (Technical data)

Approved in US/Canada

Capacity

Maximum flow rate: 6.35 GPM (24 l/min) at a 45°F (25°C) rise.

Maximum output

142,968 Btu/h (41.8 kW)

Fig. 3 Gas pressure measuring point

Venting

See chapter 2.9 for Venting on page 9.

Water

• Hot water connection (inches) - ¾”

• Cold water connection (inches) - ¾”

• Water valve material: Polymer (PPS) (Polypropylene Sulfid)

• Minimum water flow: 0.8 gallon/minute (3 l/m)

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Appliance details

• Minimum recommended water pressure: 30 PSI (2.07 bar)

• Connections: – Bottom of heater

Combustion

•NOx ≤ 55 ppm

•CO ≤ 250 ppm

•CO

level set from factory, see chapter 9.1.

Dimensions

• Depth (in): 8 ½” (220 mm)

• Width (in): 15 ¾” (400 mm)

• Height (in): 23 ½” (600 mm)

• Weight: 47 pounds (21 kg).

Gas types

Natural Gas. LP Gas. Converting the gas type can only be done by a certified gas technician with a calibrated CO

analyzer. Call

CEC for conversion instructions.

Voltage

120 V AC (50/60 Hz)

Amperage

IDLE - 40 mA Operation - ≤ 2,5 A

Noise

≤ 50 db (A)

UNPACKING THE 250 SX HEATER

This heater is packed securely. The box includes:

• Pressure relief valve

• Bracket for wall hanging the heater

• Exhaust vent adaptor (with 4 screws and gasket provided)

• Combustion air inlet adaptor (with 3 screws and gasket provided)

• Plastic decal shields for covering front cover screws and control panel, installer should affix these decals to the front of the unit after installation is complete. See Fig. 4

• Installation manual

• Product registration card.

Do not lose this manual. Please complete and return the enclosed product registration card.

Before installing the unit, be certain you have the correct heater for your type of Gas - Propane or Natural Gas. Identification labels are found on the

shipping box, and on the rating plate which is located on the right side panel of the cover.

To remove front cover

• Loosen the two Philips head screws located on front panel (beneath plastic decal shields if they are already attached, see Fig. 4)

• Lift front cover panel upward and remove.

Safety devices

• Flame failure device (ionization flame rod sensor)

• Pressure relief valve (supplied with heater)

• Over heat prevention (temperature limiter).

Water resistant

IP X4 (protection against water drops)

Plastic decals

Fig. 4 Remove front cover

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2.3 Dimensions and Minimum installation clearances

Fig. 5 Dimensions

1 Cover 2 On/Off switch 3 Reset button 4 LCD display 5 Program button 6 Temperature buttons

Fig. 6 Minimum clearances

Model 250 SX

TOP (A) 12”

FRONT (B) 4” BACK 0”

SIDES 4”

FLOOR (C) 12”

VENT DIAMETER 3”

Table 1 Minimum clearances

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2.4 General rules to follow for safe operation

B 1. You should follow these instructions when you

install your heater. In the United States: The installation must conform with local codes or, in the absence of local codes, the National Fuel Gas Code ANSI Z223.1/NFPA 54. In Canada: The Installation should conform with CGA B149.(1,2) INSTALLATION CODES and /or local installation codes.

B 2. Carefully plan where you install the heater. Correct

combustion air supply and vent pipe installation are very important. If not installed correctly, fatal accidents can be caused by lack of air, carbon monoxide poisoning or fire.

B 3. When the unit is installed indoors and ROOM

SEALED (twin pipe) it is permitted to be located in bathrooms, bedrooms and occupied rooms that are normally kept closed. See chapter 2.9. If the unit will be installed indoors and use indoor combustion air, the place where you install the heater must have enough ventilation. The National Fire Codes do

not allow UNSEALED gas fired water heater installations in bathrooms, bedrooms or any occupied rooms normally kept closed. See

chapter 2.5 and 2.8.

B 4. You must vent your heater. See section on

VENTING.

B 5. The appliance must be isolated from the gas

supply piping system by closing its individual manual gas shutoff valve (not supplied with heater) during any pressure testing at pressures in excess of ½ Psig (3.5 kPa). The appliance and its gas connection must be leak tested before placing the appliance in operation.

B 6. Keep water heater area clear and free from

combustibles and flammable liquids. Do not locate the heater over any material which might burn.

B 7. Correct gas pressure is critical for the optimum

operation of this heater. Gas piping must be sized to provide the required pressure at the maximum output of the heater, while all the other gas appliances are in operation. Check with your local gas supplier, and see the section on connecting the gas supply.

B 8. Should overheating occur or the gas supply fail to

shut off, turn off the gas supply at the manual gas shut off valve, on the gas line. Note: manual gas shutoff valve is not supplied with the heater.

B 9. Do not use this appliance if any part has been

underwater. Immediately call a qualified service technician to inspect the appliance and to replace any part of the control system and any gas control which has been underwater

2.5 Proper location for installing your heater

Carefully select the location of the water heater. For your safety and for proper heater operation, you must provide combustion air to the heater and a proper exhaust vent system. Follow the guidelines below:

B 1. Locate the heater where venting, gas and

plumbing connections are feasible and convenient.

B 2. It is strongly recommended that the heater be

installed as a ROOM SEALED heater (twin pipe). If the heater will be installed as an UNSEALED heater (single pipe) than National building codes require that you do not install this appliance in bathrooms, bedrooms or any occupied rooms normally kept closed. Heaters that are UNSEALED require a considerable amount of combustion air, see chapter 2.8. If installing the heater UNSEALED within a laundry room, be certain that the dryer is properly vented. Failure to properly vent a dryer could result in a gradual accumulation of lint build up inside the combustion chamber of the heater.

B 3. The hot water lines should be kept short to save

energy. Centrally locating the water heater is best. It is always best to have hot water lines insulated.

Warning: The water in this water heater is cold and always remains cold except for the times that hot water is being used DO NOT INSTALL IN AN AREA WHERE IT COULD FREEZE. Drain the heater entirely if freezing temperatures are anticipated in area where heater is installed by disconnecting both the inlet and outlet connections at the bottom of heater. To prevent any freeze damage, introduce short bursts of compressed air (20-40psi) through these connections to remove the residual water in the horizontal pipes and water valve.

Warning: Flammable materials, gasoline, pressurized containers, or any other items or articles that are potential fire hazards must NOT be placed on or adjacent to the heater. The appliance area must be kept free of all combustible materials, gasoline and other flammable vapors and liquids.

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2.6 Clearances

The 250 SX is design certified for installation on a combustible wall (see 2.7 Mounting installation) provided the floor covering below the heater is noncombustible. For installations in an alcove or closet, maintain the minimum clearances to combustible and non-combustible materials listed below. See also Fig. 6.

A. Top 12 inches (306 mm) B. Front 4 inches (102 mm) C. Back 0 inches D. Sides 4 inches (102 mm) E. Bottom 12 inches (306 mm)

Clearances from any exhaust vent pipe are dependent upon the clearance requirements of the stainless steel vent pipe manufacturer. Single wall stainless steel (AL29-4C) vent pipe (vent type rated for Category III appliances) must be used when exhaust venting this appliance. See 2.9 Venting.

2.7 Mounting installation

Warning: before starting installation:

B check that there are no loose parts

inside the appliance

B ensure that gas pipe, gas valve, mixer,

fan and burner have no damage and are properly fitted.

Front cover should be removed (see instructions on page 4) in order to inspect

components visually.

The 250 SX is design certified for mounting on a wall. Secure the wall mounting bracket provided with the heater to a wall surface. See Fig. 7. Do not install this appliance on a carpeted wall or over floor covering which is combustible, such as carpet. The heater must be mounted on a wall using appropriate anchoring materials. If the mounting bracket is unable to line up on two wall studs it is recommended that support board(s), either 1x4's or ½" (minimum) plywood first be attached across a pair of studs and then the heater should be attached to the support boards. The heater should be kept level on the wall surface. See Fig. 7. Expansion and contraction of piping due to changing water temperature in the pipes imparts movement to the heater which, if mounted directly to a brittle, friable board, such as plasterboard, can cause failure of mounting.

Before installing the unit, be certain you have the correct heater for your type of Gas - Propane or Natural Gas. Identification labels are found on the

shipping box, and on the rating plate which is located on the right side panel of the cover.

Fig. 7 Mounting the heater

2.8 Combustion air requirements

The 250 SX is a sealed water heater and it is recommended that outdoor combustion air be piped to the unit. When combustion air is piped to the unit (TWIN PIPE SYSTEM) the combustion air pipe system may be constructed of either 3" PVC, aluminum or galvanized pipe. See Fig. 11, 12 and 13. Select a point for building penetration being sure that the necessary clearance on the outside of the building, between the combustion air pipe and the exhaust vent terminator of the appliance, can be maintained, see Fig. 16. NOTE: Observe all local building codes when penetrating a building wall.

NOTE: The combustion air inlet location on the side of a building must never be less than 3 feet away from the units exhaust vent terminator, see Fig. 16 Table 3.

The heater has the ability to operate without combustion air being piped to it from the outside, provided there is an adequate amount of combustion air available in the room area. Observe the following instructions concerning combustion air when following the SINGLE PIPE (exhaust venting only) SYSTEM only and follow Fig. 14 and 15 for proper setup.

• Appliances located in unconfined spaces: – a) An unconfined space is one whose volume is

greater than 50 cubic feet (1.42 cubic meter) per 1000 Btu per hour (292.81 Watts) of the combined rating of all appliances installed in the space. That would be 8750 cubic feet (247.8 cubic meter) for the 250 SX alone.

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– b) In unconfined spaces in buildings of

conventional frame, masonry, or metal construction, infiltration air is normally adequate to provide air for combustion.

• Appliances located in confined spaces: The confined space must be provided with two permanent openings, one commencing within 12 inches (304.8mm) of the top and one commencing within 12 inches (304.8mm) of the bottom of the enclosure. Each opening must have a minimum free area of one square inch per:

– 1000 Btu/hr (292.81 Watts) if all air is taken from

inside the building

– 2000 Btu/hr (585.62 Watts) if all air is taken from

the outside by horizontal ducts

– 4000 Btu/hr (1171.24 Watts)if all air is taken from

the outside by direct openings or vertical ducts

Or the confined space must be provided with one permanent opening or duct that is within 12 inches (304.8mm) of the ceiling of the enclosure. This opening must have a minimum free area of one square inch per:

– 3000 Btu/hr (878.43 Watts) if all air is taken from

the outside by a direct opening or vertical duct.

Louvers, grills and screens have a blocking effect. If the effective free area is not known, increase the sizes of your openings by 75% if your louvers are wood and by 30% if your louvers are metal. Refer to the National Fuel Gas Code for complete information. In buildings of tight construction all air should be taken from outside.

Establish vent clearances that comply with the vent manufacturer's specifications. In all cases follow local codes. See table 2.

2.9 Venting

Warning: Do not reduce the vent

(exhaust and combustion) pipe sizes and do not common vent with any other vented appliance or stove.

NOTE: This appliance's exhaust must be vented to the outside with a sealed 3" stainless steel vent pipe (AL29-4C). The appliance's flue gasses are under positive pressure and must travel through a stainless steel 3" pipe that is sealed gas tight. Stainless steel vent pipe is equipped with sealing gaskets for ease of installation, proper safety and durability. The heater shall not be vented in combination with any other appliance; the appliance must only be vented with a dedicated sealed vent system.

Caution: The vent system must be

installed by a qualified agency in accordance with these instructions. If improperly installed a hazardous condition such as explosion or Carbon Monoxide poisoning could result. CEC will not be responsible for improperly installed appliances.

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The maximum flue gas exhaust temperature on the 250 SX is 437°F (225°C)

Venting Options

Room s ea l ed (twin pipe)

Open combustion (single pipe)

Exhaust vent is always fan assisted. Installation of exhaust vent and combustion air piping may be run vertically or horizontally and in separate directions if required.

* A maximum of three 90 degree elbows are permitted in the total vent length. The total vent length must be reduced by 1 ¼ feet for every 45° elbow used in the vent system. ** Stainless steel (AL29-4C) vent pipe is manufacturerd by Z-Flex, Protech and Heat Fab. NOTE: clearance distances are variable depending if the vent pipe is installed in an enclosed or unenclosed space, the exhaust flue gas temperature and the orientation of the vent pipe.

Exhaust vent diameter and material

3 inch stainless steel (AL29-4C) sealed vent pipe

* Exhaust vent maximum length

26 feet (8 m) with one elbow. Less 2½ feet for each additional 90° elbow

* Exhaust vent minimum length

3 feet 3 inch PVC,

3 feet See

Combustion air pipe diameter and material

aluminum or galvanized pipe

chapter 2.8

Combustion air pipe maximum length

26 feet (8 m) with one elbow. Less 2½ feet for each additional 90° elbow

See chapter 2.8

Vent pipe clearances within an unenclosed space

** See vent manufacturer's specifications

Vent pipe clearances within an enclosed space

** See vent manufacturer's specifications

Table 2

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The appliance should be located as close to the point of termination as possible. The maximum vent length is 26 feet (8 m) with one 90 degree elbow. Subtract 2½ feet from the total vent length for each additional 90° elbow used (a maximum of three 90° elbows are permitted in the total vent length), or subtract 1 ¼ feet for every 45° elbow used. Horizontal sections of vent must pitch ¼" for every foot of horizontal length and be supported at 4 foot intervals with overhead hangers. Note: Listed thimbles or collars are necessary to pass through wall and ceiling partitions. If the vent system passes through combustible areas where the vent clearance requirements cannot be maintained, it is permissible to chase straight sections of sealed 3 inch single wall vent through 4 inch (or greater) Type-B vent. The distance to combustibles using this chase technique is 1 inch. Note: Type-B vent should never

be used as the actual exhaust vent system for the appliance, as it is not gas tight.

Minimum exhaust vent size and length

The use of a 90 degree elbow is equivalent to 2 ½ ft in vent length. The use of 45 degree elbow is equivalent to 1 ¼ ft in vent length.

page 24. See error code to confirm error, correct the problem and then reset the heater before operating.

Attaching the exhaust and air inlet connection adaptors to the top of the heater

Fig. 10

Fig. 8

Maximum exhaust vent and combustion air inlet lengths

Fig. 9

Note: reduce 2½ ft for each 90° elbow used after the first one, reduce 1 ¼ ft for each 45° elbow.

Vent Safety System

The 250 SX will shut down if inadequate exhaust venting is detected or a lack of combustion air is provided to the unit; see troubleshooting section on

Fig. 11

B Attach the flue gas exhaust accessory (8 705 504

114) to the top of the unit (position 1) using the 4 screws and gasket provided, and fully insert 3" stainless steel vent pipe into the accessory and tighten the clamp (position 2).

B Attach the combustion air inlet accessory (8 705

504 115) to the top of the unit (position 3) using the 3 screws and gasket provided, and fully insert 3" combustion air pipe into the accessory and tighten the clamp (position 4). NOTE: The appliance has the possibility to mount the combustion air inlet accessory on the top right or on the top left side of the heater. The combustion air inlet that is not used must be kept sealed.

2.9.1 Venting options

Installing this water heater as a room sealed (TWIN PIPE SYSTEM) is the recommended method. Contact CEC or dealer for available vent termination kits and vent materials for this water heater.

Exhaust venting shall be done with 3” stainless steel (AL29-4C) vent pipe.

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